Preheater cyclone feed pipe design

.Dear all,

          After using AF like MSW, Tyre dust, plastice waste. Iam facing lower stage  cyclone   kiln feed pipe ,  feed box  and flap coating formation. ( TSR% 5.8 with 100 % pet coke)

        I want increase lower two stage cyclone feed pipe dia.for avoid plant stoppage due to cyclone  cone and feed pipe  jamming on basic of  below formula.

     Feed pipe dia=  k Sqrt tpd +2* castabe thickness in mm

      How  i can  calculate k for  above problem .

     Or any method for calculation feed pipe design concept.

     Best regards

     GKS